There are important limitations to frequently used methods of error measurement. Therefore, current information about the epidemiology of medical error is also limited. Adopting an observational methodology from aviation, we propose to videotape a prospective cohort of trauma resuscitations at Memorial Hermann Hospital and thoracic surgery procedures at UT MD Anderson Cancer Center to better understand the epidemiology of error. In addition to counting errors, this project will determine the relationships among teamwork and error in trauma resuscitation and thoracic surgery from the video analysis. Teamwork is a complicated phenomenon, but based upon Dr. Helmreich?s aviation and medical research, we will study specific error management behaviors that comprise teamwork. Identifying the specific error management behaviors that are related to error in medicine is a crucial step in designing a team training intervention and the data from this project will be used to design the team training intervention in project 4 (Helmreich). We hypothesize that errors during trauma resuscitation and thoracic surgery are common and that specific error management behaviors are correlated with these errors. To test this hypothesis we will: 1) videotape a prospective cohort of trauma resuscitations at Memorial Hermann Hospital and a prospective cohort of thoracic surgery procedures at UT MD Anderson Cancer Center; 2) analyze the tapes to determine the incidence of error during trauma resuscitation and thoracic surgery; 3) analyze the tapes to determine the relationships among error management behaviors and error; and 4) use the data from aims 1-3 to design the team training intervention to improve error management behaviors and decrease errors proposed in project 4 (Helmreich).